Transportation vehicles, particularly automobiles, are marketed and sold on the basis of differentiation over other competitive models. Differentiation may be by style or color, and is often accomplished by using trim panels or appliqués on the interior or exterior of the vehicle which denote different levels of luxury, price or value. These appliqués or panels may also form protective coverings for areas that protrude from adjacent surfaces. These panels are generally color-coordinated with the adjacent surfaces of the vehicle but may also be bright, reflective, wood grained, marbleized or metallized in appearance.
Originally, real wood appliqués and finished metal panels were used, however, their popularity suffered due to their high cost and limited durability. Subsequently, wood veneers and films with vacuum-deposited metal layers found favor, however, these solutions did not produce the look of luxury or the extended durability required in today's market.
Various proposals have been suggested and practiced for the manufacture of plastic composites for use as automotive interior trim and exterior trim panels or appliqués. One approach has been to form a metal or plastic substrate and apply multiple coatings thereon to produce a high gloss Class A-surfaced part. The substrates may be formed from steel, or any one of a wide range of known plastic materials such as ABS, PP, ABS/PC blends, PU, TPO, PET, PBT or other equivalent high strength plastic materials suitable for injection molding into a product shape. The coatings for such substrates may be selected from known coatings such a primer coat, an adhesion promoter, a base coat and a clear coat, and in the case of metals, an electrodeposition coat. Examples of such coatings are set forth in U.S. Pat. Nos. 4,681,811 and 5,320,869. The solvents used in such systems may cause undesirable environmental and emission problems.
Another approach is to form a paint film and inject polymeric material behind the paint film to produce a part with a desired colormatch on its exposed Class A surface. Examples of known paint film and injection molded plastic parts are disclosed in U.S. Pat. Nos. 5,432,666 and 5,009,821. Such systems may require the separate manufacture and handling of the film. Furthermore, the outer surface being a paint film may not exhibit an exceptional depth of image and may be readily scratched or abraded.
Still another approach to providing a colored plastic part is to provide an enamel coating that will reduce emissions while producing a crater resistant surface on the part being coated. One such system is set forth in U.S. Pat. No. 4,396,680. Such systems may require the use of expensive conventional coating systems and baking ovens to form a finish on the substrate that has the desired appearance.
Yet another approach is to provide laminating equipment in which a color layer is formed by extrusion and then connected to a substrate. U.S. Pat. No. 4,349,592 discloses the use of such a technique in the manufacture of a decorative molding exterior trim part.
Various other proposals have been suggested to produce decorative trim parts and appliqués which have unique decorative patterns, high distinctness of image (DOI) and exceptional “depth of image” which give the impression of luxury and high value. “Depth of image” is herein defined as the emphasis of a decorative pattern by a preferably clear resin layer overlying it, which provides the appearance that the pattern lies deep beneath the top surface of the clear outer layer. This is derived from wood finishing where multiple layers of wax or coatings are applied and buffed out to provide a grain pattern that appears to lie well below the top surface or has depth.
For instance, U.S. Pat. No. 5,338,592 is directed at laminating a series of wood veneers to form an overlay sheet, finishing, cutting and drying the overlay to form a shape, molding a transparent resin layer onto the front surface of the wooden shape and molding a synthetic resin core material onto the rear surface of a wooden shape. However, the effort of forming the wooden veneer overlay to the desired shape is both time consuming and costly.
Similarly, U.S. Pat. No. 5,525,179 is directed at manufacturing a lining part comprising a blank having a preformed shape and a cutout with an edge, injection molding a first plastic material to form a back surface, followed by injection molding a second plastic material to form a front surface coating which also coats the edges of the part. Again, a preformed shape is disclosed.
As disclosed in the '179 reference, German Published Application 41 24 297 describes a similar process using a preshaped blank and employing polymethyl-methacrylate (PMMA) as the outer layer. However, this reference does not disclose the use of a plastic backing layer.
U.S. Pat. No. 6,444,317 is directed at preparing a laminate film including a polyolefin film layer and a primer layer and injection molding a polyolefin resin onto the polyolefin film layer to form an outer layer.
Regarding decorative wood articles, U.S. Pat. No. 6,444,319 assigned to Erwin Behr, GmbH & Co. is directed at surface coating of an interior fitting for vehicles with a lacquer or resin layer wherein a wood veneer component is inserted into a mold and spaced from the cavity so that a liquid surface coating material having at least two mixed components may be introduced into the space between the mold and wood veneer component. United States Patent Application Publications Nos. 2003/0044598 and 2003/0162045, also to Behr, disclose the use of a liquid coating material curable by UV radiation, and the application of a coating material based on vegetable-oil-modified resin and natural vegetable oils, with the addition to the coating material of ceramic micro-particles, respectively.
Finally, United States Patent Application Publication No. 2002/0007898 is directed at a method of making a molded wood part having a wood grain pattern wherein a wood fiber substrate is formed, coated with a water impermeable substrate and a pattern transferred to the substrate using a hydrographic process. A protective top coat may be applied over the pattern. One example of a hydrographic process is disclosed in U.S. Pat. No. 4,010,057 wherein a thin film on which a pattern is printed is floated on the surface of a liquid and the pattern is transferred onto the surface of the object by submerging the surface of the object in the liquid.
While the various methods are suitable for their intended purpose, they all involve processing considerations that either produce emissions, require heavy capital investment in facilities or require unnecessary handling of one or more layers of material in the manufacture of a decorative exterior or interior trim product and do not produce an exceptional depth of image of the decorative layer.
Thus, there is a continuing need in this field of art for an article and its method of manufacture that will obviate the above problems.